JP3070414U - Developing device for electrophotographic equipment - Google Patents

Abstract

(57) [Problem] To provide a developing device provided with a developer stirring rod capable of preventing high-speed rotation of a developer in a downstream region in a developer conveying direction. SOLUTION: In a developing device of an electrophotographic apparatus, spiral stirring rods 3 and 5 which have stirring screws 3a and 5a on an outer peripheral wall and convey developer from one end to the other end are rotatable in a developer container 6. At least one plate-shaped paddle fin 15 extending radially outwardly adjacent to the inner wall of the developer container 6 at the downstream end of the spiral stirring rods 3 and 5. And

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a developing device used in an electrophotographic apparatus such as a copying machine or a printer, and more particularly, to a structure of a spiral stirring rod for stirring and transporting a developer.

[0002]

[Prior art]

 The electrophotographic apparatus is provided with a developing device for visualizing an electrostatic latent image formed on a photosensitive drum with a developer. In this developing device, a developing roller is rotatably arranged near the photoconductor, and supplies the developer to the photoconductor drum via the developing roller. As the developer, a two-component developer using a toner and a carrier is often used. In this two-component developer, it is necessary to make the mixing ratio of the toner and the carrier uniform by performing sufficient mixing and stirring in order to prevent fog and density unevenness on the image. As the mixing and stirring means, as shown in FIG. 4, two spiral stirring rods 3 and 5 each having a first stirring screw and a second stirring screw are used. The bearing is rotatably supported at both ends, and a seal member 7 such as an oil seal and an oil-impregnated bearing 8 are installed in the bearing to prevent intrusion of the developer. When the toner concentration in the developer container decreases, toner is supplied from the toner container to the toner replenishing unit 9 by toner concentration detecting means (not shown), and the toner is moved by the rotation of the spiral stirring rod. The developer and the carrier are circulated and conveyed through the developer passages 10 → 11 → 12 → 13 → 10 as indicated by arrows in the figure while mixing and stirring.

[0003]

[Problems to be solved by the invention]

 However, in the conventional developing device as described above, the toner stays in the downstream region 14 in the developer transport direction, and the developer stirring efficiency (uniform toner and carrier mixing ratio) is reduced. The vicinity of the bearing portion in the downstream area 14 in the developer conveying direction is a compression area, and high pressure is applied by the action of the axial pressure of the spiral stirring rods 3 and 5, so that the developing agent enters the bearing section. Is easy to occur. Further, the developer that has entered the bearing portion stagnates, and the heat generated by the rotation of the spiral stirring rods 3 and 5 promotes wear and burnout of the seal member 7 and the bearing 8 and at the same time reduces the rotational torque due to solidification of the developer. There was a problem that caused a rise and a decrease in stirring efficiency. This phenomenon becomes remarkable when the spiral stirring rod is rotated at high speed.

In view of the above circumstances, the present invention proposes a developing device of an electrophotographic apparatus provided with a developer stirring rod capable of preventing a developer from staying in a downstream region in a developer transport direction and rotating at a high speed. Aim.

[0005]

[Means for Solving the Problems]

 The developing device of the electrophotographic apparatus according to claim 1 is provided with a stirring screw on an outer peripheral wall, and a spiral stirring rod for transporting the developer from one end to the other end is rotatably supported in the developer container. At least one plate-shaped paddle fin extending radially outward is provided at the downstream end of the spiral stirring rod.

[0006] In the developing device of the electrophotographic apparatus, the developer is scraped off by the paddle fin provided at the downstream end of the spiral stirrer bar, so that the stagnation of the developer is prevented.

According to a second aspect of the present invention, there is provided a developing device for an electrophotographic apparatus according to the first aspect, wherein the developer accommodating device includes two spiral stirring rods. The downstream end of one spiral stirring rod and the upstream end of the other spiral stirring rod are arranged close to each other, and the upstream end of the one spiral stirring rod and the other end The spiral stirrer bar is disposed close to the downstream end.

In the developing device of the electrophotographic apparatus, the developer scraped by the paddle fin provided at the downstream end of one of the spiral stirring bars is supplied to the upstream of the other spiral stirring bar. Is done. Similarly, the developer scraped from the downstream side of the other spiral stirring bar is supplied to the upstream side of one spiral stirring bar. In this way, the developer is smoothly circulated between the two spiral stirring rods, so that the developer is efficiently stirred.

According to a third aspect of the present invention, in the electrophotographic apparatus according to the first or second aspect, the paddle fin is an elastic body.

In the developing device of the electrophotographic apparatus, since the paddle fin has elasticity, the paddle fin can be provided in close contact with the inner wall of the container. Therefore, the developer attached to the inner wall of the container can be scraped out.

A developing device for an electrophotographic apparatus according to claim 4 is the developing device for an electrophotographic apparatus according to claim 1, wherein the spiral stirring bar is provided on an inner wall of the developer container. A hole is formed by exposing the downstream end, and a reverse spiral screw having a spiral direction opposite to that of the stirring screw is provided in the spiral stirring bar in the hole.

In the developing device of the electrophotographic apparatus, the reverse spiral screw acts on the developer in a direction of returning to the upstream side, so that the developer is prevented from entering the bearing portion. .

The developing device for an electrophotographic apparatus according to claim 5 is the developing device for an electrophotographic device according to claim 4, wherein the projected diameter of the reverse spiral screw in the spiral axis direction is the spiral axis of the stirring screw. It is characterized by being larger than the projected diameter in the direction.

In the developing device of this electrophotographic apparatus, the axial pressure at which the reverse spiral screw acts is larger than the axial pressure at which the stirring screw acts on the developer. Therefore, the force of the reverse spiral screw to return the developer is greater than the force of the stirring screw for the developer to enter the bearing portion, and the intrusion of the developer is more sufficiently prevented.

According to a sixth aspect of the present invention, in the electrophotographic apparatus of the fourth or fifth aspect, the reverse spiral screw is an elastic body.

In the developing device of this electrophotographic apparatus, since the reverse spiral screw can be provided in close contact with the hole provided in the inner wall of the container, the scraping ability of the developer is high.

[0017]

[Embodiment of the invention]

 Hereinafter, a developing device according to an embodiment of the present invention will be described with reference to the drawings. However, unless otherwise specified, the shapes, relative positions, and the like of the components described in this embodiment are not intended to limit the scope of the invention only to this, but are merely illustrative examples. . FIG. 1 is a schematic configuration diagram of a developing device of the image forming apparatus according to the present embodiment. FIG. 2 is a sectional view taken along line II of FIG. In the figure, reference numeral 6 denotes a developer container for storing a developer including a toner and a carrier. In the developer container 6, the developing roller 2 and the spiral stirring rods 3, 5 are provided. The spiral stirring rods 3 and 5 are rotatably supported by bearings 8 provided inside the wall of the developer container 6. The developing roller 2 is in contact with the photosensitive drum 1 as shown in FIG. A seal member 7 such as an oil seal is provided adjacent to the bearing 8. In the developer container 6, a toner supply port 9 is opened facing the spiral stirring bar 3.

On the outer peripheral wall of the helical stirring rods 3, 5, stirring screws 3 a, 5 a whose helical directions are formed respectively are formed. A partition wall 4 is provided between the helical stirring bars 3 and 5, and divides the inside of the developer container 6 into developer passages 10 and 12 in which the helical stirring bars 3 and 5 are stored. Outside the left and right ends of the partition wall 4, developer passages 11, 13 through which the developer is moved between the developer passages 10, 12 are provided. Thus, when the spiral stirring rods 3 and 5 are respectively rotated in the direction B in FIG. 1, the developer is mixed and agitated, and the arrow C direction in the figure (developer passage 10 → 11 → 12 → 13 → 10). Is to be circulated. When the downstream end of the spiral stirring rods 3 and 5, that is, the left side in FIG. 1 is the front of the developer container 6, the left end of the spiral stirring rod 3 and the right end of the spiral stirring rod 5 Paddle fins 15 extending one by one on both sides in the radial direction of the spiral stirring rods 3 and 5 are provided in contact with the inner wall of the developer container 6 in the toner retaining area (see reference numeral 14 in FIG. 4). The paddle fin 15 is a separate member from the spiral stirring bars 3 and 5 and is formed of a rubber-like elastic member.

On the inner wall of the developer container 6, on the downstream side of the spiral stirring rods 3, 5, a hole 6 a for exposing the end of the spiral stirring rods 3, 5 is formed. Are fixed to the spiral stirring rods 3, 5 in contact with the inner wall of the hole 6a. The reverse spiral screw 16 has a spiral direction opposite to that of the stirring screws 3a, 5a, and generates a force for rotating the developer to return the developer into the storage portion. FIG. 3 shows an enlarged view of the downstream end of the spiral stirring rod 3. The downstream end of the spiral stirring rod 5 has the same configuration. Assuming that the projected diameter of the stirring screw 3a in the helical axis direction (helical diameter) is d, and the projected diameter of the reverse spiral screw 16 in the helical axis direction is D, the relationship is D> d as shown in the figure. Thus, the magnitude P1 of the axial pressure of the reverse spiral screw and the magnitude P2 of the axial pressure of the stirring screw satisfy P1> P2.

Next, the operation of the developing device will be described. First, when the toner concentration in the developer container 6 is reduced, toner is supplied from a toner container (not shown) through a toner supply port 9 by toner concentration detecting means (not shown). Then, the spiral stirring rods 3, 5 are rotated in the B direction by a motor (not shown). By the rotation of the spiral stirring rods 3, 5, the developer is circulated while being stirred in the direction of arrow C in the figure. Here, in the conventional developing device, the stagnation of the developer has occurred on the downstream side of the spiral stirring rods 3 and 5 (see reference numeral 14 in FIG. 4). However, in this example, since the paddle fins 15 are formed, the developer is smoothly scraped out to the other helical stirring rods 5, 3, and the stagnation of the developer is prevented. When the developer stays, a high pressure acts on the bearing 8 on the downstream side to make it easier for the developer to flow into the bearing portion. Is prevented. Further, in this embodiment, since the reverse spiral screw 16 is provided on the inner wall of the developer container 6, a force for returning the developer to the inside of the container 6 is generated, and the developer enters the bearing 8. Is prevented. At this time, the magnitude P1 of the axial pressure of the reverse spiral screw 16 and the magnitude P2 of the axial pressure of the stirring screws 3a, 5a are in a relationship of P1> P2. Since the pressure at which the reverse spiral screw 16 attempts to return the developing agent is larger than the conveying pressure, the intrusion of the developer is more sufficiently prevented.

With the above-described measures, the retention of the developer and the intrusion of the developer into the bearing portion can be prevented, and stable mixing and agitation can be performed even during high-speed rotation. In particular, since the paddle fin 15 and the reverse spiral screw 16 are formed by rubber-like elastic members, the developer adhered to the inner wall of the container 6 and the inner wall of the hole 6a can be scraped out. As described above, the developer can be supplied to the developing roller 2 while the mixing ratio of the toner and the carrier is maintained in a uniform state, and fog and density unevenness on an image can be prevented. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention. Further, although the number of the paddle fins 15 is two in the above, the number is not limited to the above example.

[0022]

[Effect of the invention]

 As described above, in the present invention, it is possible to prevent the stagnation of the developer and the penetration of the developer into the bearing portion, and it is possible to stably mix and stir even at the time of high-speed rotation.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a developing device of an image forming apparatus according to an embodiment.

FIG. 2 is a sectional view taken along line II in FIG.

FIG. 3 is an enlarged view of a downstream end portion of the spiral stirring rod in FIG. 1;

FIG. 4 is a schematic configuration diagram of a developing device of a conventional image forming apparatus.

[Explanation of symbols]

 3,5 spiral stirring rod 3a, 5a stirring screw 6 developer container 6a hole 15 paddle fin 16 reverse spiral screw

Claims (6)

[Utility model registration claims] 1. A developing device for an electrophotographic apparatus, comprising: a stirring screw provided on an outer peripheral wall; and a helical stirring rod for conveying a developer from one end to the other end is rotatably supported in a developer container. A developing device for an electrophotographic apparatus, characterized in that at least one plate-shaped paddle fin extending radially outward is provided at the downstream end of the spiral stirring rod. 2. The developing device for an electrophotographic apparatus according to claim 1, wherein two of the spiral stirring bars are provided in the developer container, and the downstream end of one of the spiral stirring bars is provided. The part and the upstream end of the other helical stirring rod are arranged close to each other, and the upstream end of the one helical stirring rod and the downstream end of the other helical stirring rod are A developing device for an electrophotographic device, wherein the developing device is disposed in proximity to the electrophotographic device. 3. The developing device for an electrophotographic apparatus according to claim 1, wherein said paddle fin is an elastic body. 4. The developing device for an electrophotographic apparatus according to claim 1, wherein a hole is formed in an inner wall of the developer container so as to expose a downstream end of the spiral stirring rod. And a reverse spiral screw having a spiral direction opposite to that of the stirring screw is provided in the spiral stirring bar in the hole. 5. The developing device for an electrophotographic apparatus according to claim 4, wherein a projected diameter of the reverse spiral screw in a helical axis direction is:
A developing device for an electrophotographic apparatus, wherein the diameter of the stirring screw is larger than a projection diameter in a helical axis direction. 6. The developing device for an electrophotographic apparatus according to claim 4, wherein the reverse spiral screw is an elastic body.